Selective signaling system



w. T. POWELL. SELECTIVE SIGNALING-SYSTEM.

APPLICATION FILED AUG.23, I916. 1,352,217 PatentedSept. 7, 1920;

2 SHEETS-SHEET l.

222152-2227? W r Q,

H ZZUFHE W. T. POWELL.

I SELECTIVE SIGNALING SYSTEM.

' APPLICATION FILED AUG-23, 1916.

1,352,217,, Y PatentedSept. 7, 1920.

2 SHEETS SHEET 2.

UNITED STATES PATENT OFFICE. v

WINFRED "1. POWELL, OF CHICAGO, ILLINOIS, ASSIGNOR TO AUTOMATIC ELECTRICCOMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

SELECTIVE SIGNALING SYSTEM.

Specification of Letters Patent. I Patented Sept. '7, 1920.

Application filed August 23, 1916. Serial No. 116.481.

To all whom it may concern: 7

Be it known that I, WINFRED T. POWELL, a citizen of the United States ofAmerica, and a resident of Chicago, county of Cook, and State ofIllinois, have invented certain new and useful Improvements in SelectiveSignaling Systems, of which the following is a specification. 4 g

My invention relates in general to selective signaling systems, but isconcerned more particularly with selective signaling in automatictelephone systems, in which connections are established through themedium of directively controlled selector and connectorswitches.

The principal object is to provide in a system of the above generalcharacter means for. selecting the proper ringing current at the lastselector. switch just preceding the final selector or connector, therebyrendering possible the use of a single group of connectors forselectively calling the subscribers on a party line. i

Inventions along this line have been disclosed before, notably in therecently issued patent to Deakin, #1,185,635, but to the best of mypresent knowledge all previous attempts have involved the multiplying ofthe selector levels. For example, in the above mentioned patent toDeakin, each connector group is accessible to calling lines by way of asmany selector levels as there are stations on' a line.

In my improved system I provide a single group of connector switches forselectively calling each group of party lines and assign to eachconnector group a single selector level, therebyrobtaining a greateconomy in apparatus. his arrangement is made possible through the useof a new method of ringing current selection in which the proper ringingcurrent is picked out by a preliminary operation of the selector switch.

The particular means and circuit arrangement by which the foregoing andother useful ends are accomplished will be fully described hereinafter,reference'being had to the accompanying drawings, which showdiagrammatically a complete circuit connection between a callingsubstation A (Figure 1) and a called substation A (Fig. 2). The exchangeequipment used in setting up the complete connection shown comprises theindividual line switch 0, the selector E, and the connector F.

Referring now to Fi 1, the substation A may be of any suitab e type orconstruction, such, for example, as the type disclosed in British patentto T. G. Martin, No. 1419 of 1910. As shown herein it comprisesessentially the receiver 2, transmitter 3, switch hook 4-,ringer 5 andcondenser 6. Being an automatic substation there is also provided a pairof impulse springs 7 and 8 controlled by the impulse wheel 9 through themedium of a finger hole dial (not shown). I

The line conductors 12 and 13 of the substation A are connected at theexchange to the individual line switch C which may be of the generaltype of line switch disclosed in ritish patent to R. V. James, No.26,301 of 1906; being, h0wever,.of the particular type shown in UnitedStates Letters Patent No. 1,078,690 granted Jan.

17, 1912, to Frank Newfprt Since line switches of the above type arewell known and form no part of my invention an ex tended descriptionwill not be given. It will suffice to say here that through the mediumof line switch C the line of substation A,'when calling, is given accessto a plurality of selector switches, one of which is shown at the rightof Fig. 1 and is indicated by reference'character E.

The master switch D is of the general type of master switch disclosed inthe above mentioned British patent to James, No. 26,301 of 1906; being,however, more nearly of the particular type disclosed in the Brit- -ishpatent to Martin, No. 1419 of 1910. As

is well understood, the function of the master switch is to maintain theplungers of all the idle line switches which it controls in positionbefore the terminals of an idle trunk line. I

The selector switch E is of the general type'of selector switchdisclosed in U. S. Letters Patent No. 815,321, granted March 13,1906, toKeith, Erickson and Erickson; the side switch and private magnet, how-.ever, being omitted, and the circuits being modified to enable theswitch to operate in a system in which the impulses are delivered overthe two sides of the line in series.v

Further modifications, supplied in accordioo ance with my invention,have to do with the ringing current selection and will be describedlater on. A selector switch of theforegoing general type, as is wellknown,

' 1 group. I

- One of the lines towhlch the connector.

One of the trunk'lines to which the selector E has agcess is indicatedin the drawings by the reference characters 120, 121, 122,

and 123 and extends tothe connector switch 'F (Fig. 2), which is of thegeneral t pe of connector switch disclosed in U. S. etters Patent No.815,176, granted March 13, 1906, to Keith, Erickson and Erickson; being,however, U. S. Letters nector switch of the foregoing type may be givenaccess to a group of one hundred subscribers lines and is operable inresponse to the two last digits in a called number to establishconnection with any line in the F has access is the party line shown inthe upper half of Fig. 2 and having the line conductors 12' and 13".

bridge of the line conductors in the usual manner and are similar to thesubstation A,

which has been described, with ,the excep-' tion, however, that theringers are adapted to respond to different-frequencies of ringingcurrent. At the exchange theline conductors 12 and 13. terminate in theindividual line switch C which is similar to the line switch C (Fig. 1).

The s ecial equipment associated withthe selector and which is concernedwith the selection. of ringing current frequencies comprises the relays40, 41', and 42, which are controlled through the medium. of the usualprivate wiper 71 and the special wiper 70. These wipers exercise theircontrollingfunctions through their engagement with the I first sets ofcontacts in the 7th, 8th, 9th,

of the associated switch. Other special "provisions in the selector Ecomprise an additional winding 55 on the relay 53, whose pur ose will beexplained, and a set of sha t controlled springs 62, which are profcontacts 60 and 61.

vided in-addition to the usual ofl normal I, The springs 62 are closedonly on the tenth vertical step.

A' to A, inclusive. The generator R detion wanted, as

of the Iparticular type disclosed in atent No. 13,901, reissued- April13, 1915, to Frank Newforth. A con-.

The four substa-. tions A, A A and A are connected in The generators R,R R and R deliver ringing currents of different frequency and areadapted to actuate, respectively, the r1ngers105, 205, 305, and 405, atsubstations livering referably current of a frequency of 33 cyc es persecond is normally in serv- I ice, but any one of the other generatorsmaybe selected, de endin on the substa- Will be in ly explained in thedetailed descriptions of the operation.

For supplying current for operating. and V talk ng purposes I have showna battery B, havmgits positive pole ounded. Ass0- mated with the.connector I have shown an interrupter I and a busy signalingmachine Qwhich are of the usual type and perform the same functions as thesamenamed pieces offipparatus in other automatic systems.

avlng given a eneral description of the apparatus involved I will nowproceed to an explanation of the operation of the system. F or thispurpose it will be assumed t at the subscriber at substation A desiresto obtain connection with the subscriber at 90 substation A, this beingthe complete circuit connection shown in the drawing. Inasmuch as agreat deal of the apparatus shown is well'known in the art, having beenfully described in the'publications previously referred to, theoperation will be described in a more or less general manner, thedetails being given only in sofar as they are concerned with myinvention.

Referring to Fig. 1, when the subscriber at substation A removes hisreceiver to initiate the call, an energizing circuit is completed overthe line conductors 12and 13, for the line relay 16 of the line-switchC. Upon attracting its armature, the line relay 16 closes a circuitforthe pull-in winding 17. Upon energizing, the pull-in winding operatesboth the plunger arm 21,. and the cut-ofi armature 22; the formerthrough the medium of its plunger (not shown) 11 forcing the banksprings 30-33, inclusive, into engagement, respectively, with contacts34-4-37, inclusive; and the latterdisconnecting the -'line conductors 12and 13, respectively, from ground and from the line relay 118 16. By theengagement of bank springs 30 and 33, respectively, with contacts 34 and37, the line conductors 12 and 13 are extended to the (jlimble woundline relay 50 of theselector The line relay 50 is accordingly energizedover the loop. circuit including substation A and, upon attracting itsarmature, closes a circuit for the slow acting release relay 51. Uponenergizing in turn, the relay 51 com- *1!!! pletes a holding circuit forthe line switch G which may be traced as-follows: ground at G", contactsprings 63 and 64, contact. 35, bank spring 31, and holding winding- 18to battery B. Since the line relay 16 is 136 [taken place in slowacting, it retains its armature to maintain the pull-in winding 17energized until after the above holding circuit has been on these testcontacts the said line is made busy. By the engagement of bank spring 32with contact 36 the master switch D is operatedjn well knownmanner toadvance the plungers of all the remaining idle line switches intoposition before the terminal of the next idle trunk line.

The foregoing operations whereby the line conductors 12 and 13 have beenextended to the line relay 50 of the selector E have response to theremoval of the receiver at substation A. The calling subscriber may nowmanipulate his dial in accordance with the first digit of the desirednumber, which digit is to determine the frequency of ringing current tobe applied to the called'line by means of a preliminary operation of theselector E, all as previously mentioned. Since it is required that thegenerator R'be selected, this generator 1 being the one .correspondingto substation A, the first digit of the called number will be the digit0. When the calling device dial is operated in accordance with thisdigit the impulse springs 7 and 8 are separated momentarily ten timesthereby interrupting a like number of times the energizing circuit ofthe line relay 50.

At each interruption of its circuit the line relay 50' is deenergizedmomentarily and sends an impulse from ground through thewinding 54 ofthe slow acting relay 5'3 and the winding of the vertical magnet 58 inseries. The vertical magnet, in response to these impulses, operates tostep up the switch shaft until the wipers 70, 71, 72, and 73 arrive atthe tenth horizontal level of bank contacts. The relay 53 is energizedin series with the vertical magnet and beingslow acting retains itsarmature during the series of impulses. Upon the first .upward movementof.the shaft the off normal contact 60 is closed thereby completing acircuit for the relay 57 which extends from ground Gr by way of contactsprings 63, 64, and 65, the contact springs 66 and 67 of the nowenergized relay 53 and the off normal contact 60 to the winding of thesaid relay 57. Upon energizing, the relay 57 locks itself independent ofthe relay 53 by means of its upper set of contact springs, and by meansof its lower set of cuit for the rotary magnet 59 which is held open'during the vertical operation of the switch by the relay 53.- At thispoint it should be mentioned that by the closure of 56 is shortcircuited and remains -t1ve for the present.

contact springs prepares a cir rela' 56, whose right hand terminal isjoined to t e holding circuit offline switch C and.

is therefore grounded, is connected in series with the relay 57, thecircuit passing through the interrupter contact 88 of the rotary magnet.The junction point 89, however, has already been connected to ground Gas previously described so that the relay VVhenthe slow acting relay 53.deenergizes pletes by means of its contact springs 66 and 68 thepreviously mentioned circuit of the rotary magnet, extending from groundG. Upon energizing, the rotary magnet operates to rotate the wipers 70,71, 72, and 73 inopera at the end of the series of impulsesit'comintoengagement with the first set of bank contacts of the tenthhorizontal level. Near the end of its stroke the rotary magnet alsobreaks, at its interrupter contact 87, the locking circuit of relay 57;and at its interrupter contact 88, the circuit of the line switchingrelay 56. Upon deenergizing, the relay 57 breaks the energizin circuitof the rotary magnet which accordingly retracts its armature to againclose the interrupter contacts 87 and 88. The operation now depends onthe grounded or non-grounded condition of the test contact with whichthe private wiper 71 is in engagement. Since the wipers were raised tothe tenth horizontal level before rotation the private wiper 71 is nowin engagement with bankcontact 81. Current for the energization ofrelays 40 and 37 in series now flows over the following path: ground atG right hand winding of relay 40, bank contact 81, private wiper 71,contact spring 91 of relay 56 and its resting contact, interruptercontact 88, off normal contact 60, and the winding of relay 57 tobattery. B. A branch of the above circuit ma .be traced from ground G byway of the r1ght hand windin of relay 41 and the off normal springs 62closed on tenth Vertical step) to the junction point 92, where it joinsthe previously traced circuit. It follows that relays 40 and 41 (inparallel) are energized in series'with relay 57 via the winding of relay40 to battery B, thereby providing a locking circuit for relay 40. it

should be mentioned here that the right hand windings of relays 40 and41 are of low resistance so as to prevent the energization of the muchhigher resistance line switching relay 56, which as previously mentionedis also in series with relay 57.

Upon the reenergization of'relay 57 the usual manner.

rotary magnet circuit is not again com plcted at this time because ofthe energized condition of relay 53 which was brought about as follows:When the wiper'70 came into engagement with bank contact 85, si-

-multaneously with the engagement of bank contact 81 by wiper 71, acircuit was completed which extended from ground G by way of bankcontact 85, wiper 70, contact springs 96 and 97 of relay 12, winding550i relay 53, off normal contact 61, and the release magnet 52 tobattery B. Upon the closure of the above circuit the relay 53 and therelease magnet 52 are energized in series, the former preventing theclosure of the rotary magnet circuit, as previously mentioned, and thelatter operating to restore the selector switch to normal position inthe A branch of the circuit com. pleted over wiper may be traced by Wayof contact springs 96 and 98and the winding of relay 42 to battery B.Relay 42 is slow to energize (being provided with a copper slug on itscore and having a stiff adjustment) inorder to allow time-for theoperations just described to take place. Upon finally attracting itsarmature, relay 42 short circuits the right hand windings of relays 40and 41 by means of its upper three contact springs and thegroundconnection at G; and also brings its contact spring 99 intoengagement with contact spring 98, whereby the latter spring isseparated from contact springs 96 and 97. A locking circuit forrelay 42may now be traced over the following path: ground at G conductor 95,.contact'springs 99 and 98, and the winding of relay 42 to battery B.

To sum up the operations brought about in response to the calling of thefirst digit, the relays 40, 41-, and 12 have been energized and lockedto ground G and the selector E has been restored to normal.

Thecalling subscriber may now operate his calling device in accordancewith the second digit of the desired number, which for convenience hasbeen assumed to be the digit 1. In response thereto the selectorswitch'is controlled as before to raise its wipers 7Q, 71, 72, and 73 tothe first horizontal level of bank contacts, after which the wipers arerotated into engagement with the first set of bank contacts of the firstlevel. Upon the deenergization of the rotary magnet after the firstrotary step, the operation now as before depends upon the grounded ornon-grounded condition of the test contact with which the private wiper71 is in engagement.

Assuming that the trunk line terminating in the first set ofcontacts ofthe first level is idle, the test contact will not be ground-- ed andconsequently there will be no circuit completed for the relay 57 and theline switching relay 56 will no longer be short .circuited. The saidswitching relay will wiper 71 from itsnormal connection at the windingof relay 56 to the holding circuit at junction point 102; anddisconnects the incoming line conductors from the line relay 50 andextends them by way of the line wipers 72 and 73, bank contacts 76 and77, and conductors 122 and 123 to the double wound line relay 130 of theconnector-F.

The line relay 130 is accordingly ener-g gized over the callingsubscribers loop, and, upon attracting its armature, completes a circuitfor the slow acting release relay 131. Upon energizing in turn, therelay 131 prepares a circuit for the vertical and rotary magnets 132 and133 in the usual manner and also completes a new holding circuit whichmay be traced as follows: ground G, contact springs 146 of relay 131,conductor 121, bank contact 75, private wiper 71, contact spring 91 andits working contact to junction point 102, where it joins the previouslydescribed holding circuit extending back to the line switch (A A branchof the above circuit extending from junction point by way of the windingof switching relay 56, the interrupter contact- 88, the off normal.contact 60 and the winding of relay 57 to b ttery whereby the saidswitching relay is maintained energized to prevent the release of theselector the slow acting relay 51 of the selector switch has had time todeenergize.

The calling subscriber may now manipulate his calling device inaccordance" with the third digit of the desired number, thereby causinganother series of interruptions of his line circuit. Responsive to theseinterruptions the line relay 130 deenergizes a cor responding number oftimes and sendseach time an impulse from ground at-Gr to the slow actingrelay 139 and the vertical magnet 132 in series, side switch wiper 142being in its first position. The vertical magnet, in response to theseimpulses, steps u the shaft until the wipers 160, 161, and 162 standopposite the horizontal level of bank,

contacts in which the line of substation A terminates. Relay 139, beingslow acting,

retains .its armature during the series of impulses and maintains acircuit from At the end of the series of impulses, the

relay 139 deenergizes andbreaks the circuit of the private magnet, whichlatter controls the side switch wipers in the usual manner to advancethem to theirsecond po-.

sition."

- The subscriber at substationfi' ma now .operate his dial in accordancewit the fourth and final digit of the desired number,

resulting as before in deenergizations of the line relay 130. Now,however, side switch wiper 142 being in its second position, the linerelay sends impulses tothe slow acting .relay 139in series with therotary magnet .133.' The rotary magnet operates in responselo theseimpulses to rotate the wipers 160, 161, and 162- until they rest,respec- I tively, upon bank contacts 163, 164, and 165,

.1 these contacts formingthe terminal of the line of substation A. inthe bank of connector'H. The private magnet 138'andthe wiper cut-ofirelay 136 are energized during the final series of impulses asbefore',the latter disconnecting the line wipers during rotation and the former,upon 'deenergizing, controlling the side switch wipers to advance themto their third position, it being assumed that the line of substation Awas idle when called. I

As side switch wiper 1 43 comes into en- "gagement with its thirdposition contact point, a circuit is completed for the cut-off lows:ground at G", side switch wiper 143 (in third position), wiper 161, bankcontact 164, and winding 18' to battery B. By the closure of the abovecircuit the cut-ofl armature 22 ,is operated to disconnect the lineconductorsj12' and '13, respectively, from ground and from the linerelay 16. Ground at Gr also extends to multiples-of bank contact 164 inthe banks of other connectors of the group, thereby making the line ofsubstation A busy to other calls. A

By the engagement of the side switch wipers 144 and 145 with their thirdposition contact points the connection between the calling and calledsubstations is completed, relay 136 being denergiz-ed. By the engagementof side switch wiper 142 with its third position contact point, acircuit is completed for the ringing relay 137 in series with theinterrupter 1, whereby ringing'current from generator R is projectedintermittently out over the line of substation A to operate the signal105 in bridge thereof. The path for the ringing current may. be tracedas follows: ground at G, generator R, contact springs 103 of relay 40,contact springs 104 of relay 41, contact springs 112 of line switchingrelay 56, wiper'70, bank contact of ringing relay 137, contact springs107, wiper 160, bank contact 163, the called subscribers line and,substatlon ringers in bridge thereof, bank contact 165, 'wiper 162,contact'sprlngs 108, and contact springs. 109 to ground at G. Aspreviously mentioned,

the ringer 105 at substation A is the rin er adapted to respond to theparticular requ'ency of ringing current delivered by generator R. I

The subscriber at substation A has nowestablished the requiredconnection with the line of substation A and the bell at the lattersubstation is being rung toattract the attention of the calledsubscriber. When the called subscriber removes his receiver from thehook a circuit iscompleted for the double wound back brid e relay 141 inthe well known manner. 'l pon attracting its armature, relay 141 closesa circuit for the ring cut-ofi" relay 135 which relay locks itself toground at G and alsoopens the circuit of the ringing relay 137, therebystopping the ringing operation. As a further result of the 'energizationof relay 141 the incom- "ing line conductors 122 and 123 are reversed asregards their connection with the windings of line relay 130. The latteroperation is withoutimportance inthe system shown here, although it isprovided in case it is desired to operate meters orsim'ilar apparatus. I

The calling and called subscribers. may now converse without furthereffort. Current for the transmitter at substation A is supplied throughthe windings of the line relay 130, whilecurrent for the transmitter atsubstation A .issupplied through the windings of the back bridge relay141.. The voice currents follow the path shown in the heavy lines which,itis thou ht,'will be apparent without further ampliiying theexplanation.

, When the conversation is completed both subscribers willhang up theirreceivers. By the replacement of the receiver at substation A thecircuit of the line relay 130 of the connector F is broken. Upondeenergizing,

relay 130 breaks the circuit of relay 131,

which relay, upon deenergizing in turn, closes; a circuit for therelease magnet 140, whereupon the connector F is restored to normal inthe usual and well known manner. As a further result of thedeenergization of relay 131, ground G is removed from the holdingcircuit extending back to the selector E and the line switch G] Theselector and line switch therefore are also restoredto normal. Inaddition the relays 40, 41, and 42, whose locking circuits have beensupplied with-ground over the holding all the apparatus will have beenrestored to -normal in readiness for another call. 74, trunk conductor120, contact springs 106 Y The operation of a connector switch such asconnector H when connection is attempted with a busy line is well knownand has circuit, retract their armatures whereupon been fullydescribed-in the publications previously mentioned. Since my inventioninvolves nothing new in connection with this feature of the operationthe description thereof will be omitted.

Having described the operations incidentto the establishin of aconnection with subscriber A, I wil now describe briefly the operationof signaling the Substations -A A and A. Since all the substationsmensubstation A requiring the selection of generator R the first digitto be called is the digit 7.. Since the bank contacts 78 and 82 of theseventh level are both permanently grounded, the selector E will beoperated and released and the relay42 will be locked up as previouslydescribed, but neither of the relays and 41 will be operated. -Withboththese relays denergized the generator R is in service, as-will bereadily apparent upon tracing the circuit. If substation A is wanted,the first digit called is the digit 8. It will be observed that theright hand winding of relay .41 is connected to the bank contact 79 ofthe eighth level. Consequently, when the selector E' is operatedinresponse to the calling of the diglt 8 and is released as before, therelay 41, in addition to the relay 42, will/be energized. With r'ev .lay41 energized and relay 40 deenergized,

the generator R corresponding to substation A is in service. Assumingfinally that substation A is wanted, the proper digit to be called forthe frequency selection is the digit 9. The right hand windingof relay40 being connected to the bank contact 80- of the ninth level, the saidrelay i0 is energized to select the generator It will be observed thatwhether the first digit called is 7, 8, 9, or 0, the relay 42 isoperated and locked up inlany case ,with the result that the right handwindings of relays -10 and 41 are short circuited by ground G.

This is donein order to prevent these relays from operating on thesecond digit of it called number, in case they were left (1e energizedafter the first digit was called. It would not be 'suflicient merely toopen the circuits of theserelays, for the bank contacts 78, 79, 80,- and81 must have ground potential on them in order to permit the selector Eto pass over the first contacts in the seventh, eights, ninth and tenthlevels when it is operated in response to the second digit of a callednumber and the selection of an idle trunk is required. Having describedmy invention What I consider to be new and desire to have protected byLetters Patent will be pointed out in the a pended claims.

What claim as my invention is: y 1. In a telephone system, meanscompria. ing a selector and connector switch. for connecting a callingand a called line, together j with means individual to said selector forselectively signaling the stations on the called line controlled in apreliminary operation of the selector switch separate from the trunkselecting operation thereof.

2. In a telephone system, means compris- .ing a selectorandconnectorswitch for connecting a'callmg and a called l1ne, togetherwithmeans individual to said selector for selectively signaling the stationson the called line controlled in a preliminary operation of the selectorswitch,

tor after the preliminary operation 'thereof and before the connectionis completed.

3. In a telephone system, a party line,

means including a selector switch and a connector swltch for extending aconnection to said party line, means individualv to said selector for.selectively signaling the. sta

tions onsaid party line, and means for giv and i means for automaticallyreleasing saidselecing said selector apreliminary movement to Idetermine the character of the signaling 0p-- eration and for thenoperating said selector to extend the connection.

4..In 'a telephone systenna party line, .7 mearisQmcl'udi'ng a selectorswitch and 'a connector switch for extending a connection to said partyline, means individual to said selector for selectively signaling thestations on said party line, means for giving said selector apreliminary. movement to determine thecharacter of the signalingoperation, andmeans for automatically releasing" said; selector afterthe preliminary movement thereofand com'pletedl 5. In a telephonesystem, a plurality connector switches, a'.' plurality of ringingcurrent generators, a selector switch, means before the connection is YJ for causing successive operations of said. selector to select'one ofsaid generators and one of said connectors, and means for. automaticallyreleasing said selector between successive operations thereof.

6. In a telephone system, a selector switch and a plurality of connectorswitches acces sible thereto, a plurality of ringing current generators,and means for operating said selector in response to two digits of acalled number to select one of said generators and 'one of saidconnectors.

7. In a telephone system, a selector switch and a plurality. ofconnector switches accesgenerators, means for operating said selector 1nresponse to one digit of a called number to select one of saidgenerators and means j sible thereto, a plurality of ringing .currentfor'operating said selector-in response to' a succeeding digit of thecalled number to select one of said connectors.

8. In a telephone system, a selector switch having vertical and rotarymotion, groups of connector switches accessible to said selector, saidgroups selectable in the vertical movement thereof, ringing currentgenerators also selectable in the vertical movement of said selector,and means for causing sue-- cessive vertical movements of said selectorto select one of said said connector groups.

9. In a telephone system, a connector switch, a selector switch forextending connection'to said connector, ringing current generatorsselectable by said selector, and means for causing successive operationsof said selector to select'one of said generators and to extend theselected generator to. said connector.

10. Ina telephone system, a plurality of trunk lines each extending to aconnector switch, a selector switch having access to said trunk lines, aplurality of ringing cur-- rent generators, and means for causingsuccesslve operations of said selector to select one of saidgeneratorsand to connectthe selected generator to one of said trunklines.

11. In a telephone system, a connector switch, a'selector switch forextending connection to said connector, ringing current generatorsselectable by said selector, means for causing successive operations ofsaid selector to select one of said generators and to extend theselected generator to said connector, and means for automaticallyreleasing said selector between successive operations thereof.

12. In a telephone system, a-plurality' of trunk lines each, extendingto a "connector switch, a selector switch having access to said trunklines, a plurality of ringing current generators, means for causingsucces- SlVe operatlons of said selector to select one of saidgenerators and to connect the se-- lected generator to one of said trunklines, and means for automatically releasing said selector betweensuccessive operations thereof. v

13. In a selective signaling system, the combination with a plurality ofringing current generatorS,-of means controllable by a callingsubscriber for selecting one of said generators, a trunk line commonto'aplurality of said means for extending connection to a called line,said means adaptedto select a generator in one operation and to extend aconnection to said trunk line in a separate operation, and means forapplying a selected generator to the called line via a conductor of saidtrunk line.

14; In a selective signaling system, four generators arranged in pairs,a relay for selecting either pair, a second relay for segenerators andone of switch, having wipers for use in connectlng lecti-ng eithergenerator of the selected pair,

and means whereby the selected generator is 1 applied to a subscribersline.

15. In a selective signaling system, four generators arranged in pairs,a relay for selectingeither pair, a second relay for selecting eithergenerator of the selected'pair,

means whereby said relays are controlled by, a callingsubscriber, andmeans whereby the,

selected generator is applied to a called line ,to signal asubscriberthereon.

1T6. In a telephone system, an automatic -'a calling anda called line, aplurality of stations on the called-line; a plurality of ringing currentgenerators .for selectively signaling said stations, and relayscontrolled 1 in, the movement of said wipers by said switch, said relaysprovided with means whereby they conjointly accomplish the selection ofany oneof said generators.

17. In a telephone system, means ing a plurality of automaticswitches-each having wipers for connecting a calling and a called line,a plurality of stationson the called line, a plurality of ringingcurrent generators for selectively signaling said stations, and relaysassociated with one of.,said

mama

switches and controllable'by the movement of the wipers of said switch:when operated by the calling subscriber, said relays providedwith meanswhereby they conjointly control the selection of any one 'of saidgenerators.

18. In a telephone system, means for connecting acalling and a calledline including a plurality of trunk lines each terminating.

in 'a connector switch, a plurality of stations on the called line, aplurality of ringing current generators for selectively signaling saidstations, means whereby the calling subscriber selects one ofsaidgenerators in one operation and one of said trunk lines in aseparate operation andmeans whereby the selected generator is extendedover a conductor of the selected trunk line to theassociated connectorswitch. v

19. In a telephone system, a plurality of selector switches each havingmovable ter minals, fixed multiple terminals in eachselector accessibleto the. movable terminals thereof, fixed non-multiple terminals in eachselector also accessible to the movable terminals thereof, and selectiveringing equipof selector switches, trunk lines connecting the two kindsof switches, ringing current generators for selective signalingassociated with said selectors, and means in each selector for selectingone of said generators in response to one digit and for extendingconnection therefrom over one of sa1d trunk lines to one of saidconnectors, and means 'for'operating the selected connector in responseto another digit to connect with and signal a called line. 21. In atelephone system, a connector switch, a' selector-switch for extendingconnection tosaid connector, ringing current generators selectable bysaid selector, means for causing successive 'OPGIYMJIOIIS of sandselector to select one of said generators and to combination with aplurality of ringing current generators, of means controllable by acalling subscriber for selecting-one of said generators, a trunk linefor extending connection to a called line, having a pair or talkingconductors and means for applying a selected generator to thecalledline,.separate from the talking conductors via a con-- ductor ofsaid trunk line, said last means comprising an automatic progressivelymove able switch at each end of said trunk line.

23. In a selective signaling system, four generators arranged in pairs,a relay for selecting either pair, a second relayfor selecting eithergenerator of the selected pair,

means whereby said relays are controlled by a calling subscriber, andmeans whereby the selected generator is applied to a called line tosignal a. subscriber thereon, said last means comprising an automaticprogres sively movable switch.

24. In a selective" signaling system, four generators arranged in pairs,a'relay for selecting either pair, a second relay for selecting eithergenerator of the selected pair, means whereby said relays are controlledby a' calling subscriber, and means whereby the selected generator isapplied to'a called line to signal a subscriber thereon, said last ameans comprising a plurality of automatic progressively movableswitches.

25.. In atelephone system, .an automatic switch for use in connecting a'calling and a called, line, a plurality of stations on the called line,a plurality of ringing current generatorfor selectively signaling saidstations, relays controlled by said switch, said relays providedwith'means whereby they conjointly accomplish the selection of any oneof said generators, and a second automatic switch for completing aconnection from the selected generator to the "called line.

26. In a telephone system, a plurality I of selector switches eachhaving movable terminals, fixed multiple terminalsin each selectoraccessible to the movable terminals thereofffixed non-multiple terminalsin each selector also accessible to the movable terminals thereof,selective ringin equipment said movable and non-mu tiple xed terminals,and connector switches accessible to said selector switches andselectable through the cooperation of said movable and multi plefixed-terminals.

. 27. Ina selective signaling system, a plurality of sources of currentof difierent char- I acter, a plurality of lines, a pluralityof sig- 1nals on each'line corresponding to said "different sources, a pluralityof trunk lines each terminating in a progressively movableautomaticswitch, said switches having access to said lines, anotherprogressively movable automatic switch having access to said trunklines, means for selecting one of said current sources, means foroperating said last switch for selecting one of said trunk lines and itsassociated automatic switch and for estab- .lishing a connection overtheselected trunk 1 line from the selected current source to theautomatic switch, said switch having access to said lines, anotherprogressively movable automatic switch having access to'said trunklines, means including relaysindividual to said last switch forselecting one of said current sources, means for operating said lastselected switch, and means for then operatswitch for selecting one ofsaid trunk lines and its associated automatic switch and forestablishing a connection over the selected trunk line from theselectedcurrent source to the selected switch, and means for thenoperating the selected sitch to connect the selected current source toone of'said lines to operate a desired signal thereon.

29. In a selectivesignaling system, a pair of line conductors, aplurality of current sources, a plurality of signaling devicescorresponding to said sources connected to both conductors, an auxiliaryconductor, a switch for connecting said auxiliary conductor with any oneof said sources, and means for placing the connected auxiliary conductorinto connection with one of said lineconductors, whereby anyone of saidsignals may be operated;

30. In a selective signaling system, a pair of line' conductors, aplurality of current sources, a plurality of signaling devicescorresponding to said sources connected to both erated, and means forautomatically conconductors, an auxiliary conductor, a switch trollingthe operation of said switch over said for connecting said auxiliaryconductor with line conductors for the purpose set forth. 10 any one ofsaid sources, means for placing Signed by me at Chicago, Cook county,

5 the connected auxiliary conductor into con- Illinois, this 12th day ofAugust, 1916.

nection with one of said line conductors,

whereby any one of said signals may be op- WINFRED T; POWELL.

